How To Test Apple Connectivity
How IP Addressing on the Internet Functions
When using the Internet, a Public IPv4 address, such as 233.150.54.211, or an IPv6 address, such as 2000:f5cc:26af:22ef:db6:264:91a5:fe1c, may be obtained. This can be verified at https://test-ipv6.com/. However, for those who are not technically inclined, conveying these addresses, or even referring to MAC addresses like aa:d1:be:a6:a1:a6, can lead to errors and quickly become complex. Furthermore, this method does not provide historical data, especially when previous issues arose.
Navigating the Internet
In order to visit a web page, such as https://bogisich-shields.io, a DNS server is initially accessed to convert the host portion (bogisich-shields) combined with the Top Level Domain (io) of the URL into an IP address, such as 100.237.67.58. Your computer and browser actually transmit its type with all web requests, for example: Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; AS; rv:11.0) like Gecko
Understanding the Significance of Default Gateways
The default gateway is typically an automatically configured address via DHCP. A default gateway, such as 192.0.0.31 (although they usually end in .1 or .254 depending on the scope size), is where your computer sends all its traffic to be routed onwards. For IPv6, an in-depth discussion is available on how-to-fix-ipv6-connectivity/, but it can be checked on Mac or Linux with:
IPv4 Routes and the Host IPv4 Route Table (inc. VPN)
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 192.0.0.31 UGScg en0 128.0/1 172.18.12.193 UGSc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v4 address space.
IPv6 Routes and the Host IPv6 Route Table (inc. VPN)
netstat -rn -f inet6 | egrep -i "default|2000::/3"
If you have IPv6 active the above should return at least one route (as per below) via a known interface such as “en0 " on a Mac.
default fe80:7979:ffad:fc71:4a5f%en0 UGcg en0 default fe80::%utun0 UGcIg utun0 default fe80::%utun1 UGcIg utun1 default fe80::%utun2 UGcIg utun2 2000::/3 utun3 USc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v6 address space.
Debugging DHCP for both IPv4 and IPv6
To get a look at the low level DHCP configuration (Mac/Linux):
ipconfig getpacket en0
...
domain_name_server (ip_mult): {227.240.128.82, 158.245.219.250}
end (none):
...
So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but…
ipconfig getv6packet en0
DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr aa:d1:be:a6:a1:a6
DNS_SERVERS (23) Length 32: 2606:4700:4700::1111, 2001:4860:4860::8844
DOMAIN_LIST (24) Length 0: Invalid
SERVERID (2) Length 10: DUID LL HW 1 Addr 71:02:c8:bc:01:bc
}
Resolving Issues with Wired and Wireless Connections
When it comes to transmitting data to your router, you might be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.
Troubleshooting Tips for Apple macOS / OSX
Regardless of whether you are running OSX/macOS version 10.14.5, 11.0.1, or 12.2.7, there are various tools available for troubleshooting. However, these manual actions and scripts do not provide a set of correlated values over time. This is where automated remote troubleshooting becomes particularly useful, especially for teams that embrace remote work and the concept of Work From Anywhere (WFA).
Useful Built-in Scripts
A very useful tool on OSX/macOS is the sudo wdutil info command, which provides a dump of current wireless settings in the CLI, and can be configured to generate specific logs for troubleshooting. In addition, the sysdiagnose tool can be used to generate a wide range of logs, although many of them are point-in-time only in relation to wireless, similar to wdutil.
To run it in the background and generate logs in /var/tmp/<blah>.tar.gz, use the commandsudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can usesudo /usr/bin/sysdiagnose, but be aware of the file sizes, which are around 300MB or so.
Possibly Helpful Videos
P.S. Tips For Remote Network and Client Support
Digital work requires reliable connectivity. Whether for low latency or regular data streams, Wi-Fi, DNS, and network issues cause teams to lose time and productivity. Even worse is when support teams waste time trying to recreate and isolate issues! See how PanSift saves time, money, and frustration on all sides with instant remote troubleshooting 🏠🏝🛰.
